Field of the Invention
Exemplary embodiments of the present invention relate to a power headrest apparatus, and more particularly, to a power headrest apparatus capable of automatically adjusting vertical and forward-backward positions of a headrest, which is provided at the upper end of a vehicle seat back, using respective motors.
Description of the Related Art
In general, a driver seat, an occupant seat, and seats as other occupant seats, which are installed in front of and behind a vehicle interior, have various comfort devices for convenience of occupants.
The comfort devices have a sliding function of adjusting a seat cushion by the forward and backward pushing/pulling of the seat cushion, a reclining function of adjusting the inclination of a seat back corresponding to the back of the seat, according to the body types of occupants, and a seat height adjustment function of adjusting the height of the seat cushion so as to be suitable for the body sizes of occupants.
In addition, a headrest apparatus, which includes a headrest for supporting the head of the occupant at the upper end of the seat back, is typically applied to the vehicle seat.
The headrest apparatus has a function of adjusting the vertical and forward-backward positions of the headrest so as to be suitable for the body type of the occupant.
The function of adjusting the vertical and forward-backward positions of the headrest may be performed by a manual method using the operation force of a user or by a motor-driven method using a motor. A power headrest apparatus has a structure that adopts the motor-driven method and is well known in the related technical field.
In connection with the motor-driven type power headrest apparatus, Japanese Patent Laid-open Publication No. H05-0056827 discloses a power headrest apparatus in which a headrest is tilted in forward and backward directions by the operation of an actuation mechanism along with the driving of a motor.
However, the power headrest apparatus disclosed in the above patent document adjusts the forward-backward position of the headrest through the structure in which the headrest is tilted in forward and backward directions instead of in a horizontal direction. For this reason, it is difficult to adjust the forward-backward position of the headrest so as to be suitable for the body types and sensitivities of occupants.
In addition, when a large load is suddenly applied to the headrest as in the rear-end collision of a vehicle, a considerable torque is applied to the actuation mechanism for tilting in the state in which the headrest is tilted. Accordingly, there is a high possibility that the actuation mechanism is damaged, and there is a high possibility that the head and neck of an occupant are secondarily damaged when the actuation mechanism is damaged.
Meanwhile, Korean Patent Laid-open Publication No. 2006-0134430 discloses a power headrest apparatus which adjusts the forward-backward position of a headrest by moving a spiral rod, connected to the headrest, in forward and backward directions by the driving of a motor.
However, the power headrest apparatus disclosed in the patent document has the structure in which an amount of forward-backward movement of the headrest depends on the length of the spiral rod. For this reason, it is impossible to secure the amount of forward-backward movement of the headrest enough to satisfy sensitivities of occupants, and thus it is necessary to increase the width of the headrest in the forward and backward directions thereof in order to secure a sufficient amount of movement.
[Patent Document 0001] Japanese Patent Laid-open Publication No. H05-0056827
[Patent Document 0002] Korean Patent Laid-open Publication No. 2006-0134430